Life history evolution in evening primroses (Oenothera): Cole's paradox revisited

Persistent Link:
http://hdl.handle.net/10150/280409
Title:
Life history evolution in evening primroses (Oenothera): Cole's paradox revisited
Author:
Evans, Margaret Eleanor Katharine
Issue Date:
2003
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Why some organisms reproduce just once in their lifetime (semelparity), while others reproduce more than once (iteroparity), has been a central question of life history theory since it was posed by Cole (1954). I used comparative studies at large (phylogenetic) and small (demographic) scales to address this question in a group of evening primroses (the Sections Anogra and Kleinia, genus Oenothera, Onagraceae) found in the arid and semiarid region west of the 100th meridian in North America. In the phylogenetic study, I found that changes in habit were not associated with the changes in aridity that I expected, based on the classic demographic model of Charnov and Schaffer (1973). Instead, this study suggested that changes to the annual habit were associated with increased temperature. I propose that temperature is an important factor influencing the favorability of the annual habit via the effect that temperature has on growth rate. The remaining two studies, comparing the performance of a closely-related desert annual and desert perennial in natural and experimental settings, also indicated that temperature correlated with habit. Using demographic data from natural populations, I evaluated seed banking and iteroparity as alternative means of bet hedging. I found evidence that bet hedging occurs via seed banking in both populations, and may occur via post-reproductive survival in the perennial populations. The demographic data did not clearly show the patterns expected to favor one form of bet hedging over the other. Based on an analysis of climate data, I suggest that cold temperatures are unfavorable to the annual habit. I compared the performance of the same species pair directly in two common environments. In this reciprocal common garden experiment, the annual outperformed the perennial when conditions were good, and when conditions became stressful relatively early. The annual, with lower leaf mass per area, more rapid above ground growth, and accelerated phenology, exhibits the classic stress-avoiding strategy of desert annuals, explaining the conditions under which it excelled. Relative to the annual, I describe the perennial as a stress-tolerator, and discuss water and temperature stress as two forms of stress it may excel at tolerating.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Ecology.; Biology, Genetics.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Ecology and Evolutionary Biology
Degree Grantor:
University of Arizona
Advisor:
Venable, D. L.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleLife history evolution in evening primroses (Oenothera): Cole's paradox revisiteden_US
dc.creatorEvans, Margaret Eleanor Katharineen_US
dc.contributor.authorEvans, Margaret Eleanor Katharineen_US
dc.date.issued2003en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractWhy some organisms reproduce just once in their lifetime (semelparity), while others reproduce more than once (iteroparity), has been a central question of life history theory since it was posed by Cole (1954). I used comparative studies at large (phylogenetic) and small (demographic) scales to address this question in a group of evening primroses (the Sections Anogra and Kleinia, genus Oenothera, Onagraceae) found in the arid and semiarid region west of the 100th meridian in North America. In the phylogenetic study, I found that changes in habit were not associated with the changes in aridity that I expected, based on the classic demographic model of Charnov and Schaffer (1973). Instead, this study suggested that changes to the annual habit were associated with increased temperature. I propose that temperature is an important factor influencing the favorability of the annual habit via the effect that temperature has on growth rate. The remaining two studies, comparing the performance of a closely-related desert annual and desert perennial in natural and experimental settings, also indicated that temperature correlated with habit. Using demographic data from natural populations, I evaluated seed banking and iteroparity as alternative means of bet hedging. I found evidence that bet hedging occurs via seed banking in both populations, and may occur via post-reproductive survival in the perennial populations. The demographic data did not clearly show the patterns expected to favor one form of bet hedging over the other. Based on an analysis of climate data, I suggest that cold temperatures are unfavorable to the annual habit. I compared the performance of the same species pair directly in two common environments. In this reciprocal common garden experiment, the annual outperformed the perennial when conditions were good, and when conditions became stressful relatively early. The annual, with lower leaf mass per area, more rapid above ground growth, and accelerated phenology, exhibits the classic stress-avoiding strategy of desert annuals, explaining the conditions under which it excelled. Relative to the annual, I describe the perennial as a stress-tolerator, and discuss water and temperature stress as two forms of stress it may excel at tolerating.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Ecology.en_US
dc.subjectBiology, Genetics.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineEcology and Evolutionary Biologyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorVenable, D. L.en_US
dc.identifier.proquest3108898en_US
dc.identifier.bibrecord.b44825134en_US
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